Polycythemia vera (PV)
- Is one of a related group of blood cancers known as “myeloproliferative neoplasms” (MPNs) in which cells in the bone marrow that produce the blood cells develop and function abnormally.
- Begins with one or more acquired changes (mutations) to the DNA of a single blood-forming cell. This results in the overproduction of blood cells.
The incidence rate of PV varies worldwide, ranging from approximately 0.5 to 2.5 new cases per 100,000 people each year.
The average age at which PV is diagnosed is about 60 to 65 years old. PV is uncommon in individuals younger than 30 years old.
What You Should Know
- Hematologists and oncologists are specialists who treat people who have PV or other types of blood cancer.
- PV is a chronic disease; it is not curable, but it usually can be managed effectively for very long periods.
- Medical supervision of individuals with PV is important to prevent or treat complications.
What You Should Do
- Talk with your doctor about your diagnostic tests and what the results mean
- Talk with your doctor about all your treatment options and the results you can expect from treatment.
- Ask your doctor whether a clinical trial is a good treatment option for you.
How Does PV Develop?
The DNA (genetic material) of a developing stem cell in the bone marrow is damaged. This is called an “acquired mutation.”
- Stem cells form blood cells (white cells, red cells and platelets).
The mutated cell leads to uncontrolled blood cell production, especially red cells.
- Because stem cells have the capability to form not only red cells, but also white cells and platelets, any combination of these cell lines may be affected.
The signs, symptoms and complications of PV occur because there are too many red cells and, often, too many platelets in the blood. An increase in the number of white cells does not predispose the patient to an increased risk of infection or cause other significant effects.
- Too many red blood cells can make the patient’s blood more viscous (thick) so the blood does not flow efficiently. High platelet counts can contribute to the formation of clots (thrombi).
Although researchers don't fully understand what causes PV, almost all PV patients have a mutation of the JAK2 (Janus kinase 2) gene. This mutated gene likely plays a role in PV's onset. However, researchers are still studying its precise role as the cause of the disease.
For most people who have PV, there are no obvious reasons (risk factors) why they developed the disease. Most patients with PV don't have a family history of the disorder, although occasionally more than one family member has the disease.
PV occurs more often among Jews of Eastern European descent than among other Europeans or Asians. The average age at which PV is diagnosed is about 60 to 65 years. It is uncommon in individuals younger than 30 years.
Source: Polycythemia Vera Facts. Reviewed by Ruben A. Mesa, MD, FACP.